useWindowDimensions() returns the window's width, height, scale and fontScale. Unlike a one-off Dimensions.get('window'), it keeps them in state, subscribes to Dimensions' change event, and re-renders only when one of the four values differs. fontScale is the user's text-size setting, and it behaves differently from a resize. Raising it to 130% with adb shell settings put system font_scale 1.3 while the book page of Responsive Layout was open logged:
LOG window 411.4 x 914.3, fontScale 1.2999999523162842 -> wide=false largeText=false
Two surprises. fontScale is missing from the configChanges of the template's MainActivity, so Android recreated the activity and React Native 36,878 mounted a fresh root view (logcat showed a new Running "main"): component state started over. And 1.3 arrived as 1.2999999523162842, so the first version's test, fontScale >= 1.3, never saw large text; compare against a value between the steps.